Rooibos Tea

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Rooibos Tea

Common Names

  • Redbush tea (South Africa)
  • Rooibosch (Netherlands)

For Patients & Caregivers

How It Works

Although lab studies suggest rooibos tea is rich in antioxidants, studies in humans are very limited.

Lab studies suggest rooibos tea contains compounds that may prevent tumor growth and slow aging, but studies on this have not been conducted in humans. Some compounds isolated from rooibos leaves showed estrogenic activity. Therefore, patients with hormone-sensitive cancers should use caution before taking rooibos.

Purported Uses
  • To treat skin conditions such as acne, eczema and wrinkles
    Although rooibos is used to treat acne, eczema, and to prevent wrinkles, clinical evidence is lacking.
  • To prevent cancer
    Some lab studies suggest rooibos may inhibit tumor growth, but others indicate that rooibos leaves have estrogenic activity. Human studies are needed.
Side Effects

Case report

Liver toxicity and low platelet count: In a 37-year-old patient about to undergo laparoscopic surgery. The cause was identified as long-term large amounts of rooibos daily. The procedure was switched to open surgery instead, to reduce the number of medications that would have to be metabolized by the liver.

Elevated liver enzymes: In a 42-year-old woman who drank large amounts of rooibos tea. Liver enzyme levels normalized within 1 week after stopping ingestion.

Special Point

Rooibos tea has antioxidant effects and may interfere with the action of certain chemotherapeutic agents.

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For Healthcare Professionals

Scientific Name
Aspalathus linearis
Clinical Summary

Prepared from the dried leaves of the rooibos plant native to South Africa, rooibos tea has grown popular in western countries because it is low in caffeine and rich in antioxidants, especially the polyphenols aspalathin and nothofagin (1). It does not contain any catechins, the major flavonoids present in green and black teas (2).

In vitro and animal studies have shown that rooibos can modulate immune function (3) (4), exhibit anti-inflammatory effects (5), and prevent oxidative stress  (7). Animal studies suggest that it may prevent chromosomal aberrations (8) and tumor mutagenesis (9) (10). In other lab studies, topically applied rooibos protected against microsomal lipid peroxidation and reduced tumor formation (1) (11), and a rooibos tea extract appeared to protect against radiation damage (12). However, these effects have not been confirmed in humans.

Preliminary data suggests rooibos may inhibit angiotensin-converting enzyme in healthy volunteers (2), which may benefit cardiovascular health. However, studies in humans are very limited and further research is needed.

Rat studies suggest that prolonged exposure to rooibos may affect the reproductive system, impair fertility, or affect liver and kidney function (25). In humans, a few cases of liver toxicity with long-term use or ingesting large amounts have been reported. Because compounds isolated from rooibos leaves demonstrated estrogenic activity (22), patients with hormone-sensitive cancers should use caution before taking rooibos.

Purported Uses
  • Skin conditions
  • Aging
  • Cancer
Mechanism of Action

Rooibos was shown to enhance the activity of glutathione-S transferase and UDP-glucuronosyl transferase in rat livers  (11) (16), allowing cells to protect against oxidative stress, and to reduce the effects of hepatocarcinogens. A study of oxidative stress in rats found that serum superoxide dismutase and urine 8-hydroxy-2’-deoxyguanosine (8-OHdG) concentrations (as markers for DNA damage) were significantly reduced following administration of rooibos (17). Some studies have shown that the non-oxidized teas have greater antimutagenic effects compared to the oxidized forms. This is probably due to reduction in total polyphenol content with oxidization (11) (18) (19). The anti-inflammatory effects of rooibos are thought to be due to its inhibition of COX-2 enzyme (5).

Rooibos also modulates immune function: It induces higher IL6, IL10 and IFN-gamma levels and increases cell-mediated immunity (3); and increases IL2 levels while suppressing IL4 (4).

In other studies, rooibos significantly decreased glucocorticoid levels in rats and steroid metabolite ratios linked to metabolic disorders-cortisol:cortisone in humans and CORT:testosterone in rats (23). Hot water-soluble solids from fermented rooibos inhibited adipogenesis and influenced adipocyte metabolism, suggesting a role in preventing obesity (24).

Adverse Reactions

Case reports

Hepatotoxicity and thrombocytopenia: In a 37-year-old presurgical patient about to undergo a laparoscopic appendectomy. The cause was identified as long-term large amounts of rooibos daily. Open appendectomy under a spinal anesthetic was subsequently deemed to be the better option, as the use of multiple medications that have hepatic metabolism with laparoscopic surgery would be eliminated (27).

Elevated liver enzymes: In a 42-year-old woman who drank large amounts of rooibos tea (21). Levels normalized within 1 week after stopping ingestion.

Herb-Drug Interactions
  • CYP3A substrate drugs: In animal studies, rooibos tea induced CYP3A and may reduce serum levels of these substrate drugs (26). Clinical relevance has yet to be determined.
References
  1. Marnewick J, Joubert E, Joseph S, et al. Inhibition of tumour promotion in mouse skin by extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia), unique South African herbal teas. Cancer Lett. 2005 Jun 28;224(2):193-202.
  2. Persson IA, Persson K, Hägg S, Andersson RG. Effects of green tea, black tea and Rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers. Public Health Nutr. 2010 May;13(5):730-7.
  3. Hendricks R, Pool EJ. The in vitro effects of Rooibos and Black tea on immune pathways. J Immunoassay Immunochem. 2010 Apr;31(2):169-80.
  4. Kunishiro K, Tai A, Yamamoto I. Effects of rooibos tea extract on antigen-specific antibody production and cytokine generation in vitro and in vivo. Biosci Biotechnol Biochem. 2001 Oct;65(10):2137-45.
  5. Na HK, Mossanda KS, Lee JY, Surh YJ. Inhibition of phorbol ester-induced COX-2 expression by some edible African plants. Biofactors. 2004;21(1-4):149-53.
  6. Darvesh AS, Carroll RT, Bishayee A, Geldenhuys WJ, Van der Schyf CJ. Oxidative stress and Alzheimer’s disease: dietary polyphenols as potential therapeutic agents. Expert Rev Neurother. 2010 May;10(5):729-45.
  7. Kawano A, Nakamura H, Hata S, et al. Hypoglycemic effect of aspalathin, a rooibos tea component from Aspalathus linearis, in type 2 diabetic model db/db mice. Phytomedicine. 2009 May;16(5):437-43.
  8. Sasaki YF, Yamada H, Shimoi K, Kator K, Kinae N. The clastogen-suppressing effects of green tea, Po-lei tea and Rooibos tea in CHO cells and mice. Mutat Res. 1993 Apr;286(2):221-32.
  9. Marnewick JL, Gelderblom WC, Joubert E. An investigation on the antimutagenic properties of South African herbal teas. Mutat Res. 2000 Nov 20;471(1-2):157-66.
  10. Marnewick JL, Batenburg W, Swart P, et al. Ex vivo modulation of chemical-induced mutagenesis by subcellular liver fractions of rats treated with rooibos (Aspalathus linearis) tea, honeybush (Cyclopia intermedia) tea, as well as green and black (Camellia sinensis) teas. Mutat Res. 2004 Mar 14;558(1-2):145-54.
  11. Marnewick JL, van der Westhuizen FH, Joubert E, et al. Chemoprotective properties of rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia) herbal and green and black (Camellia sinensis) teas against cancer promotion induced by fumonisin B1 in rat liver. Food Chem Toxicol. Jan 2009;47(1):220-229.
  12. Komatsu K, Kator K, Mitsuda Y, Mine M, Okumura Y. Inhibitory effects of Rooibos tea, Aspalathus linealis, on X-ray-induced C3H10T1/2 cell transformation. Cancer Lett. 1994 Feb 28;77(1):33-8.
  13. Erickson, L. Rooibos Tea: Research into Antioxidant and Antimutagenic Properties, HerbalGram. 2003;59:34-45.
  14. Habu RAF, Mon TR, Morton JF. Volatile components of Rooibos J. Agric. Food Chem. March 1985;33(2):249-254.
  15. McKay DL, Blumberg JB. A review of the bioactivity of South African herbal teas: rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia). Phytother Res. 2007 Jan;21(1):1-16.
  16. Marnewick JL, Joubert E, Swart P, Van Der Westhuizen F, Gelderblom WC. Modulation of hepatic drug metabolizing enzymes and oxidative status by rooibos (Aspalathus linearis) and Honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas in rats. J Agric Food Chem. 2003 Dec 31;51(27):8113-9.
  17. Baba H, Ohtsuka Y, Haruna H, et al. Studies of anti-inflammatory effects of Rooibos tea in rats. Pediatr Int. 2009 Oct;51(5):700-4.
  18. Standley L, Winterton P, Marnewick JL, et al. Influence of processing stages on antimutagenic and antioxidant potentials of rooibos tea. J Agric Food Chem. Jan 2001;49(1):114-117.
  19. Van der Merwe JD, Joubert E, Richards ES, et al. A comparative study on the antimutagenic properties of aqueous extracts of Aspalathus linearis (rooibos), different Cyclopia spp. (honeybush) and Camellia sinensis teas. Mutat Res. Dec 10 2006;611(1-2):42-53.
  20. Kreuz S, Joubert E, Waldmann KH, Ternes W. Aspalathin, a flavonoid in Aspalathus linearis (rooibos), is absorbed by pig intestine as a C-glycoside. Nutr Res. 2008, Oct; 28(10):690-701.
  21. Sinisalo M, Enkovaara AL, Kivistö KT. Possible hepatotoxic effect of rooibos tea: a case report. Eur J Clin Pharmacol. 2010 Apr;66(4):427-8.
  22. Shimamura N, Miyase T, Umehara K, Warashina T, Fujii S. Phytoestrogens from Aspalathus linearis. Biol Pharm Bull. 2006 Jun;29(6):1271-4.
  23. Schloms L, Smith C, Storbeck KH, et al. Rooibos influences glucocorticoid levels and steroid ratios in vivo and in vitro: A natural approach in the management of stress and metabolic disorders? Mol Nutr Food Res. 2014 Mar;58(3):537-49.
  24. Sanderson M, Mazibuko SE, Joubert E, et al. Effects of fermented rooibos (Aspalathus linearis) on adipocyte differentiation. Phytomedicine. 2014 Jan 15;21(2):109-17.
  25. Opuwari CS, Monsees TK. In vivo effects of Aspalathus linearis (rooibos) on male rat reproductive functions. Andrologia. 2014 Oct;46(8):867-77.
  26. Matsuda K, Nishimura Y, Kurata N, et al. Effects of continuous ingestion of herbal teas on intestinal CYP3A in the rat. J Pharmacol Sci. 2007 Feb;103(2):214-21.
  27. Reddy S, Mishra P, Qureshi S, et al. Hepatotoxicity due to red bush tea consumption: a case report. J Clin Anesth. Dec 2016;35:96-98.
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